Integumentary System
Functions of the integumentary
system
• Protection from the environment-the skin is the
superficial surface of the body
• Thermoregulation-secretions from sweat glands
in the skin cool the body down
• Storage of lipids-adipose tissue (fat)
• Vitamin D synthesis
• Provides sensory info-sensory receptors located
in the skin
Fig
4.1
Adipose CT
Fig
4.2
Layers of the epidermis
Stratum basal (germinativum)-attached to
basement membrane, contains stem cells &
melanocytes
Stratum spinosum-keratinization begins
Stratum granulosum-process of adding keratin
continues
Stratum lucidum-only in thick skin
Stratum corneum-at surface of skin
Layers of dead interlocking keratinocytes
Contains large amount of keratin
Makes a dry water resistant layer
Epidermis
Fig
4.3
Thick & thin skin
• Thick skin has 5 layers in the epidermisincludes the stratum lucidum, plantar/palmar
• Thick skin has a thicker stratum corneum
Fig
4.4
Fingerprints-thick skin
• Epidermis-epidermal
ridges
• Dermis-dermal
papillae
Fig
4.4
Dermis
•
•
•
•
•
Composed of connective tissue
Highly vascular
Contain nerves and sensory receptors
Located deep to the epidermis
Has two layers:
– Papillary layer provides nutrients, O2 etc to
the epidermis
– Reticular layer-interwoven network of collage
fibers surrounding dermal organs
Papillary & Reticular layers
Papillary layer
Consists of areolar CT
provides nutrients, O2 etc to the epidermis
Tattoo ink is injected into the papillary layer
Reticular layer
– Reticular layer-interwoven network of collage fibers
surrounding dermal organs
– Wrinkles and stretch marks arise from degradation of
the reticular layer
Lines of cleavage-clinical aspect
• Collagen & elastic fibers are arranged
in parallel bundles in the skin
• Incisions parallel to the lines of
cleavage heal faster than incisions at a
right angle to the line of cleavage
Hypodermis
• Loose Ct with adipose cells
• Regional distributions of adipose in males
and females
•
•
•
•
Stabilizes position of organs
Reduces heat loss
Energy reserve
Cushion
?’s about the integument
• Text chapter 4
Accessory structures
• Hair, nails, & glands in the skin (dermis)
• Hair grows everywhere except areas with
thick skin and portions of the external
genitalia
• Hair is formed in organs called hair
follicles
• Hair give added sensory info and protects
orifices of the body (nostrils, ears)
Hair
• Types of hairs on the body:
• Vellus hairs-“peach fuzz” over most of the body
• Intermediate hairs-hairs stimulated by
hormones-pubic hair, beard, distal appendages
• Terminal hairs-hairs on head, eyebrows,
eyelashes
• Hair is dead keratinized epithelial cells
hard
keratin
follicle
Soft
keratin
hard
keratin
Fig
4.10
Glands in the skin
Fig
4.12
Sebaceous glands
• Branch off of hair follicles
• Release oily secretion on to hair
Fig
4.9
Sweat glands
• Apocrine-in the
axillary, areolae &
inguinal regions
• -secrete into hair
• Merocrine (eccrine)all over the body
– Secrete onto skin
– Smaller and more
superficial than
apocrine glands
Fig
4.14
• Mammary glands-modified apocrine
glands that release breast milk
• Cerumious glands-modified merocrine
glands that release cerumen (ear wax)
mechanism holocrine
of secretion
Type of
gland
merocrine
apocrine
Sebaceous merocrine Mammary
glands
(eccrine) & glands
Apocrine
glands
Fig
3.9
Nails
• Protect distal ends of finger & toes
• Stratum corneum forms the hyponychium
and eponychium
• Blood vessels give the pink color
Fig
4.15
Layers of the integument-review
superficial
• Epidermis-stratified squamous epithelial tissue
– Stratum corneum-thicker in thick skin-palmar/plantar
– Stratum lucidum-only in thick skin
– Stratum granulosum-contains keratin &
(melanin in people of African decent)
– Stratum spinosum-contains melanin & keratinocytes
– Stratum basal (germinativum)-contain melanocytes-melanin
• Dermis
- Papillary layer-areolar CT
deep
superficial
• Dermis
– Papillary layer- areolar CT
• Eccrine sweat glands-watery secretions
• Sebaceous glands- oily secertions
• Meissners corpuscle-sensory receptors for soft touch
– Reticular layer- dense irregular CT
• Apocrine sweat glands- smelly secretions
• Hypodermis
– Adipose CT
– Pacinian corpuscles-sensory receptors for deep
pressure
deep
Adipose CT
Fig
4.2
Burns to the skin
classification
damage
Affected organs
Appearance and
sensation
1st degree
burn
Superficial cells of
the epidermis are
killed. Dermis cells
are injured-papillary
layer
Hair follicles &
glands unaffected
Inflamed, tender
2nd degree
burn
Injury to dermisreticular layer
Hair follicles &
glands may be
affected
Blister, pain
3rd degree
burn
All dermal cells are
killed. Injury to the
hypodermis
Sensory nerves,
accessory structure,
blood vessels
destroyed
Charred, less
pain than 1st and
2nd
FYI Aging
& the Integumentary system
Changes that occur
Result
Epidermis thins-less
More prone to injury/infection
germinative cell activity
Decreased # of Langerhans
Reduced immune function
cells
Decreased melanocyte
More sensitivity to
activity
sun/sunburn
Reduced Vitamin. D synthesis Muscle/bone weakness
Decreased dermal blood
Reduced ability to regulate
supply & sweat/oil gland
temperature, dryer skin
activity
Hair follicles function
Thinner hairs, grey/white
decreases
hairs, balding
Dermis thins, elastic fiber
Weaker sagging wrinkled skin
network shrinks
Skin repairs slowly
Recurring infections
• Photos of models
• http://www.rwc.uc.edu/ap/aphome.htm
Lab 5
Adipose CT
Fig
4.2
Fig
4.9